The present invention relates to the preparation of chlorosucrose sweeteners and particularly to the preparation of such sweeteners in a stable form useful for incorporation in a variety of food and confectionery products as well as for medicinal uses.
The sweetening agent known as sucralose comprises a chlorosucrose sweetener derived from a class of compounds based upon sucrose and galactosucrose in which one or more hydroxy groups are replaced by chlorine atoms, and is described in U.K. Patent No. 1,543,167, the disclosure of which is incorporated herein by reference. Of particular interest is the compound sucralose, (4-chloro-4-deoxy-.alpha.-D-galactopyranosyl 1,6-dichloro1,6-dideoxy-.beta.-D-fructofuranoside, also known as 4,1',6',-trichloro-4,1',6'-trideoxygalactosucrose). Sucralose and the other members of its chemical family have been identified as intensely sweet, offering a sweetness several hundred times that of sucrose, and are of particular interest for use as low calorie sweeteners to replace saccharin in various products, including foods, candy, comestibles, beverages and orally received medicinals such as cough drops.
This class of compounds is generally relatively stable and inert and particularly exhibits the stability in acid aqueous solutions, in marked contrast to peptide-based sweeteners such as aspartame. Under completely dry conditions, however, sucralose which is present in a crystalline form tends to discolor in response to elevated temperatures. For example, such discoloration can be exhibited after twenty minutes of exposure of pure dry sucralose to a temperature of 100C., wherein the color changes to a pale brown.
Efforts have previously been undertaken to stabilize sucralose by various techniques. For example, in U.K. Patent Application No. 2,169,601A to Jackson, sucralose is treated by co-crystallization with a nitrogenous base and in particular compounds containing an amine group such as niacinamide or an amino acid. An alternative approach was pursued by Jackson and Jenner and disclosed in European Patent Publication No. 0,255,260, wherein crystalline sucralose was prepared and then reduced to particles of critical dimension, in particular such particles no greater than 10 microns in mean particle size with a maximum particle size no greater than twice the mean.
Neither of the foregoing approaches has been totally satisfactory as the resulting sucralose products have continued to exhibit commercially undesirable thermal instability, and in the instance of the co-crystallization with the nitrogenous base material are further qualified in their acceptability by the admixture with a material that may be of reduced sweetness sensation.
A need therefore exists to develop a truly thermally stable form of sucralose that likewise maximizes the delivery of the sweetness sensation when such material is incorporated into foods and related comestible products.